Apparatus for the production of music



y 1935-. a. F. MIESSNER 2,001,391

APPARATUS FOR THE PRODUCTION OF MUSIC Original Filed May 4, 1931 ATTOEY'.

Patented May 14, 1935 UNITED STATES 2,001,391 arraaa'rus roa' THEraonuc'non or MUSIC Benjamin F. Mieaaner, lillillburn Township, EssexCounty, N. 3., assignor to Miessner Inventions,

a corporation of New-Jersey Original application May 4, 1931, Serial No.

534,349. her 4, 1932, Serial No.

4 8 Claims. This invention relates to musical instruments and systemswherein the vibrations of tuned vibrators are translated into electricoscillations and thence into sound, and more particularly to the controlof the damping rate of such sounds. This application is filed as adivision of my prior co-pending application Serial Number 534,849,

ingapluralityofsuchdampingrates.

filed May 4. 1931, now Patent No. 1,929,031, dated October 3, 1988. Theinvention, although useful with any mode of excitation of the tunedvibrators, is illustrated in connection with an instrument of the classdescribed comprising strings caused to vibrate by percussion. Suchinstruments and improvements therein have been dis.- closed and claimedgenerally in my co-pending application Serial Number 512,399, filedJanuary :0, now Patent No. 1,929,027, dated October When the vibrationsof a plurality of vibrators-strings for example-are translated intosound by a mechanico-electro-acoustic series of translations, andparticularly when this is done by means of mechanico-electrictranslating devices in spaced relation to the vibrators, the latter arefreed of the damping influences of the resonator system ordinarilycoupled thereto in conventional instruments-in other words the impedanceof the resonator is no longer reflected into the vibrators, and thelatter are isolated from acoustic impedance. This results in a decreaseof the rate of damping of the output tones. This decrease may beexaggerated in certain cases and at certain frequencies by the action ofacoustic feed-back from the electro-acoustic translating device to thevibrators. Difierencu in damping rate between individual output tonesmay also result from. non-uniformity of the tuned vibrators themselvesand/or of their respective mountings.

It isan object of my invention to provide methods and apparatus forindividually adJustIng the damping rates of the output tones of amusical instrument of the class described. It is a further object toprovide methods and apparatus for simultaneously adjusting the dampingrates of all the tones. A still further object is the provision ofmethods and apparatus for selectively provid- Other and allied objectswill more fully appear from the following description and the appendedclaims.

In such description reference is had to the accompanying drawing, ofwhich Figure iisapattlyplanandpartlyschematic view of portions of aninstrument embodying my invention, and 1 Divided and this applicationNovem- Figure 2 is a cross-sectional view thereof taken along the line2-2 of Figure 1.

In Figure 1, I show strings I, strung for example between tuning pins 2in plank 3 and pins 4 in rear block 5, over triangular bars 6, at leastone of which latter may conveniently be electrically conductive in orderthat the strings may be connected together electrically. There may beemployed a hammer I underneath each string for vibrating the latter anda damper. I6 above each string'for stopping the vibration thereof. Sucha hammer I and a damper I6 more clearly appear, and actuating meanstherefor are shown, in Figure 2, a cross-sectional view taken along line2-2 of Figure 1. Keys I'I, pivoted as at I8, may be employed with arepeating action, not shown but well known in the art as a component ofthe grand piano, to propel hammer 1 toward string I upon depression ofthe front or leftshown end of the key. Such depression may also serve toraise arm (I, pivoted at 42; and by virtue of damper rod 43 pivoted at5i and passing through guide It, to raise damper I6 from its nor.- malposition of contact with string l.- Bar 45, supported by rods '46pivoted as at 41, may pass under the several arms 4| and connect by rod48 to pedal l8, pivoted as at 50; depression of pedal 49 thus raisingall the dampers I6 simultaneously from the strings I, according toprinci-' pies well known in the art. The dampers I6 are intended toperform the usual function of either fully permitting or efiicientlypreventing vibration of the associated strings. Excepting as to thesedampers It, the term damping" and its derivatives are herein employed intheir broader sense, denoting decay of a vibration, or its decrease withtime, whether inherent in a particularly mounted vibrator or otherwisecaused.

For translating the vibrations of the strings I into electricoscillations I show. electrically? conductive bar I, which may beinsulatedly mounted above strings I as by uprights I0 and insulatingblocks 9. Bar 3 may be electrically connected to the grid of athermionic vacuum tube 2I, which I show in Figure 1 as the first tube ofan electri-' cal amplifier including tubes 22, 23 and 2|, the last twobeing shown in push-pull arrangement.

Battery 25 is shown for exciting the filaments or by-passed resistor 29for the biasing, through high resistance 21 and potentiometer 28respectively, of their grids negatively with respect to their cathodes;likewise the filaments or cathodes of tubes 23 and 24 may be connectedto such negative terminal through condensively by-passed resistor 30. Adifferent potential from that of bar 8 is applied to strings I byconnection of one of the triangular bars 6 to a point of positivepotential in battery or source 39. Electrostatic shielding, shownschematically as Ill, may advantageously be provided at least partiallyabout the strings I and the translating and amplifying apparatus.

If now one of the keys ll be depressed, causing the associated hammer Ito be propelled toward the associated string I and the associated damperIt to be raised therefrom, such string I will be caused to vibrate atits fundamental and harmonic frequencies, producing an oscillatoryvariation in the minute electrical capacity between such string I andbar 8. This capacity in parallel with other similar capacities ischarged from source 39 through resistance 21, but by virtue of the highvalue of the latter this charge cannot change rapidly. Hence thevibration-produced variations in the capacity will produce across it anA. C. voltage substantially corresponding in its variouscharacteristics, including harmonic structure, to the vibration of themean string point below bar 8. This voltage will be seen to be appliedto the grid of tube 2 I. Amplifled by this tube, it appears acrossresistor 3| and is applied through stopping condenser 32 topotentiometer 28, whereby it may be selectively adjusted in respect ofamplitude and applied to the grid of tube 22. Again amplified by tube 22and push-pull transformer 33, it is applied to the grid of tubes 23 and24, in equalamplitudes but in opposite phases on such two grids, as willbe understood. From the output circuit of these tubes it is applied toloudspeaker 35, through the medium of transformer 34 if desired.

It will be understood, of course, that the particular amplifier systemshown is illustrative only and that any suitable form of electricalamplifier may equally well be employed'in an instrument embodying myinvention.

To regulate the damping rates of the output tones I employ mechanicalmeans for adjusting the damping rates of the vibrators themselves, whichmeans are illustrated in the figures. Thus bar 60 may be provided aboveall the strings, being mounted to a plurality of arms 6| which in turnmay be pivoted to stationary blocks 62. In-

to bar 60 above each string may be threaded a screw 63, carrying at itslower extremity pad 64 of soft material such as felt or soft rubber. Thevertical position of the bar 60 and pads 64 may be varied by rod 65,pivotally secured to one of the arms 6I as at 66', and passing throughplank 3 and between parts of the action to pedal 61, flexibly pivoted asat 69. Spring 68 may be pro-' vided to impart an upward moving tendencyto bar 60; and toothed L- shaped bar I may be provided adjacent pedal61, wherewith pedal iI may be engaged to maintain against the force ofspring 69 any desired position adjustment and whereby the upward motionof the pedal end of bar 60 may be limited.

The ends of the active portion of a string may be considered vibrationalnodes thereof, being points of no vibration for fundamental and allharmonic components. With any vibrators, pads 84 are preferably employednear a vibrational node. Consequently I have shown them above a point oneach string near its extremity.

With pedal 61 and bar ill in some definite position, for example theupmost possible position, the pad 64 above any string having aninherently slower rate of damping or vibration decay than the others maybe adjusted to press against the string with any desired force and thusto equalize the damping of the latter with that of the other strings.Again, the pad 64 above any string which tends to be sustained tovibration, as by acoustic feed-back from the loudspeaker, may beadjusted to overcome such feed-back tendency and to cause such string toapproximate the others in rate of damping. A pad not required in suchadjustment to press against the associated string may be adjusted to aposition as close to the string as possible without pressure against thelatter or without actual contact therewith. If now more rapid clampingrate than normal for all the strings be desired, pedal 61 may bedepressed and, if' desired, maintained in its new position by engagementwith toothed bar I0.

It will be obvious that the function of the pads 64 may be described asthat of reflecting impedance into the strings, and that this impedancemay be varied for all the strings by pedal 61, and

for any individual string by the associated screw' It will finally beunderstood that my invention is not to be limited by the form of thespecific embodiments disclosed, but is rather to be determined by thescope of the following claims.

I claim:--

1. In combination in a musical instrument, a plurality of tunedvibrators; selectively operable impulse exciting means therefor; amechanicoelectro-acoustic translating system for translating from saidvibrators substantially the entire output sound of said instrument, saidsystem having portions in spaced relationship to said vibrators andoperating in accordance with vibratory variation of such spacedrelationship, whereby said vibrators are substantially isolated fromacoustic impedance; and mechanical impedance means coupled to saidvibratorsfor reflecting thereinto mechanical impedances to simulatereflected acoustic impedance.

2. In combination in a musical instrument without a resonator, aplurality of tuned vibrators; selectively operable impulse excitingmeans therefor; a mechanico-electric-acoustic translating system fortranslating from .said vibrators substantially the entire output soundof said in- .impedances to approximate the reflected impedance of aresonator.

' 3. In combination in a musical instrument without a resonator, aplurality of tuned vibrators; selectively operable impulse excitingmeans therefor; a mechanico-electro-acoustic translating system fortranslating from said vibrators substantially the entire output sound 0!said instrument, said system having portions in spaced relationship tosaid vibrators and operating in accordance with vibratory variation ofsuch spaced relationship, whereby said vibrators are substantiallyisolated from acoustic impedance;

and a plurality of mechanical impedance means adjustably coupled to theindividual said vibrators for reflecting mechanical impedances into theseveral vibrators to prevent sustention of vibration thereof by acousticfeed-back from said translating system.

BENJAMIN F. MIESSNER.

